1. Technical Field
The present invention relates to an image display device, and a control method therefor.
2. Related Art
A previously-known image display device such as projector carries therein a plurality of photo sensors on a rear projector screen. For use in such an image display device, proposed is a method of automatically enhancing the brightness and color balance of video light uniformly in the screen based on detection signals of the photo sensors. As an example, refer to Patent Document 1 (JP-A-7-162790). For the aim of minimizing the reduction in enhancement precision resulting from variations among a plurality of sensors, there is another method of using a single sensor to detect light collected by a plurality of light-gathering units provided as alternatives to sensors, and performing enhancement based on the resulting detection signal. As an example, refer to Patent Document 2 (JP-A-2002-214700).
Even with the methods of Patent Documents 1 and 2, however, it remains generally quite difficult to enhance brightness based on the side of increasing the brightness, and there is thus no choice but to use any portion of the lowest brightness as a basis for the entire brightness enhancement. This consequently causes a problem of reducing the brightness of the entire image as a result of brightness enhancement. This is also true for color enhancement, and due to the necessity for using the lower-chroma side as a basis for color enhancement, i.e., the color of most whitish as a basis, the color reproduction area is thus narrowed.